Thoughts on pole buildings
There is a company in the area that will build pole buildings for around $47 sqft. This includes a finished concrete slab, metal roof, metal siding, a few windows, garage doors, etc.
This would be for a shop/garage.
I am in a very high-cost-to-build area so this is a very affordable and attractive number.
My question is about the longevity of the structure. Mainly the poles. They must use a more toxic version of pressure treated lumber if they’re counting on it lasting long-term in the ground? Or is it just that the buried posts are so large, they’ll take forever to rot away?
I’ve seen a couple of these types of buildings go up. Pretty impressive to have a working space in 10 days of labor.
Any thoughts?
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If you're planning to use the pole building more or less "as built", heating and cooling it infrequently, I think it's a good choice. If you're thinking you're going to take this building and retrofit insulation and air sealing to equal a modern house build, it's probably not going to work out cheaper in the end. This has been discussed a lot.
Joe,
If enclosed space for storage or a workshop is what you want, pole-buildings and quonset huts work fine.
To answer your direct question, the posts are often engineered and milled to exact dimensions. On my largest "pole" building (24x48x16 to the truss bottoms), the posts were treated for the bottom 8', with a plastic jacket on the portion that actually ended up in below ground. I bored 24" holes for them, had a 12" thick concrete footer at 48" below grade and concrete fill to ground level. The treated portion is rated for "direct ground contact", unlike most of what is available at the home centers.
FWIW, I erected the building single-handed, using only a tractor and a rental boom lift. It took me about a month.
And it had a close brush with an EF-3 tornado just days after I finished the shell. Aside from losing a brand-new 18'x10' roll-up door, the building was unscathed.
You’d probably want to use CCA treated poles, which will hold up better than the more friendly AC2 treatment you usually see these days for things like decks. CCA is restricted more now, but it’s still available for things like utility poles and certain “critical structural” applications which I would think would include pole barn poles.
There are a lot of issues with sealing and insulating a pole barn, although it can be done. I have a neighbor with such a building that has a second floor apartment in it and it works ok for them. You’ll probably need to use more spray foam in such a building than you would in a regular stick built home due to having more oddball connections needing to
Be sealed.
Bill
Admittedly I don't know too much about pole buildings, but I did do some metal siding recently and looked at a bunch of the RR buildings videos to get some tips. While there I looked at some of their current builds and they don't sink the poles in the ground at all, but drill brackets that sit on concrete footings to hold up their posts. Looks like a good way to avoid the rot issue and the coatings you'd otherwise need.
For a shop/garage you can't beat them. I have a circa 1966 pole barn that I'll be reroofing this year and it fits the bill for serviceable storage space. My neighbor just completed one with the poles sitting above grade as described above so that eliminates the rot issue. However he says he's going to try and heat and cool the space, which in our zone 5 climate has many issues that have been noted here.